object TestCase {

        //now matter if you put (abstract) class or trait it will fail in all cases
        trait MapOps[T]

        //if fs was reduced to List (generic type with one parameter) then the code compiles
        //if you inherit from MapOps[T] instead of MapOps[F] then code compiles fine
        implicit def map2ops[T,F](fs: Map[T,F]): TestCase.MapOps[F]{val m: Manifest[T]; def is(xs: List[T]): List[List[T]]} = new MapOps[F] {
          //if you remove this line, then code compiles
        lazy val m: Manifest[T] = sys.error("just something to make it compile")
        def is(xs: List[T]) = List(xs)
      }

      def main(args: Array[String]): Unit = {
        println(Map(1 -> "2") is List(2))
      }

    }
